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<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
</body>
<script>
    'use strict';//严格代码模式（变量必须先定义后使用）
    var x =100;
    var x = 'abc';
    name = '张三';
    console.log(x);//在控制台输出，用于开发时的测试
    console.log(name);
</script>
</html>